JPH044191A - Thermal recording material back coating film - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer ribbon having good resistance to heat and sliding properties and hardly adhering to a thermal head by a method wherein a back coating layer is made of a film obtained by blending a polyparabanic acid and a reaction product of a silicone compound having reactive group with an organic di-isocyanate. CONSTITUTION:A polyparabanic acid (PPA)(I) and a reaction product (II) of a silicone compound having reactive group with an organic di-isocyanate are blended. The blend ratio of the product (II) per 100 of the (I) is 0.5 - 30 (wt.%). A coating film is formed on the rear surface of a substrate by a method wherein a varnish containing the PPA and the aforesaid reaction product in an organic solvent is applied on the substrate, dried, and heated, or by an alternative method wherein the varnish is casted on the substrate, dried, and heated. In this manner, a back coating film having good resistance to heat and surface smoothness, a small coefficient of friction, and improved sliding properties is made available.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a heat-sensitive recording material backcoat film and a thermal transfer ribbon provided with the same, and more specifically, to a backcoat film containing polyparabanic acid as a component. Concerning sex improvement technology.

[Prior art] In the thermal transfer method for thermal recording, thermal energy is applied from the back side of the base sheet, so the back side of the base sheet has sufficient heat resistance and the thermal head does not stick to the back side. It is necessary. If there is such adhesive,
The recording quality is significantly degraded, and the film support is eventually burned into the thermal head, making it impossible to feed the thermal transfer recording medium. There is a growing demand for faster transfer speeds.

The base sheet is made of -M and polyethylene terephthalate resin (PET). The PET base sheet has excellent transparency, mechanical properties, insulation properties, etc., but generally has insufficient heat resistance.

The back surface of the base sheet is coated with a resin solution such as polyurethane resin, acrylic resin, modified cellulose, etc., which has relatively good heat resistance, to form a back coat layer (heat resistant layer). In addition, there is also a heat-resistant layer in which a modified product, which is a reaction product of a silicone compound having a reactive organic functional group and an organic incyanate and does not have a free incyanate group, is added to a film-forming resin. (Japanese Unexamined Patent Publication No. 62-220385).

[Problems to be solved by the invention] However, - the back coat layer has insufficient heat resistance and tends to stick to the thermal head, and requires higher energy to be applied to the thermal head due to the demand for quality improvement. However, there was a problem in that it was not possible to meet such demands.

The present invention aims to eliminate the drawbacks of such prior art.

[Means for Solving the Problems] To explain the present invention in detail, in the present invention, the back coat layer is formed by mixing polyparabanic acid with a reaction product of a silicone compound having a reactive group and an organic diisocyanate. Polyparabanic acid has good heat resistance, but its slipperiness with the thermal head is somewhat insufficient when used alone, so we improved its slipperiness, thereby improving heat resistance. It was possible to obtain a coating film that was durable, had good surface smoothness, and had a small abrasion coefficient.

(I) Polyparabanic acid (hereinafter referred to as PP) used in the present invention
A) is a synthetic resin represented by the following general formula.

This PPA is usually composed of hydrogen cyanide and the general formula 0CN-R-NGO [R represents a divalent organic group, as described in, for example, Japanese Patent Publication No. 4920960. It can be produced by hydrolyzing poly-1 (iminoimidazolidinedione) of the following general formula, which is obtained by reacting the following diisocyanate.

It corresponds to R in the general formula of the cyanate compound, and R or [R is the same as above. ] In the present invention, the above poly(iminoimidazolidinedione)
75% or more of partial hydrolyzate (P I P
A) can also be used.

R in the general formula of PPA is the diisoR', R
2, R'', R', R', and R6 are hydrogen atoms or methyl groups, X and Xl are bonds, CH2, oxygen ring CH.

It is.

The diisocyanate includes m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4
'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 2゜4- and 2.6-h lene diisocyanate (TDI), p-xylylene diisocyanate], m-xylylene diisocyanate, toridine diisocyanate (TODI), 3 .3'-dimethyl-4,4'-biphenylene diisocyanate, 3-3
'-Dimethoxy-4,4'-biphenylene diisocyanate, 4,4'-diphenylmethane diisocyanate (
MDI), 4,4'-diphenyl-isopropylidene diisocyanate, 4-(4-isocyanatecyclohexyl)phenyl isocyanate, 4-incyanate benzyl isocyanate, 4,4' diphenylsulfone diisocyanate, 4,4' diphenyl ether diisocyanate, Tetrafluoro-p-phenylene diisocyanate, tetrafluoro-m-phenylene diisocyanate, 4,4' diisocyanate octafluoro-biphenyl and durene diisocyanate; 3,3'
-dimethyl-4,4'-methylenebis(cyclohexyl isocyanate), 1,4-diisocyanate cyclohexane, inphorone diisocyanate, 4,4'-dicyclohexyl diisocyanate and 1,3-bis[a
+ α'-Dimethylisocyanate methylcobenzene; alkylene groups, arylene groups, cycloalkylene groups having 2 to 10 carbon atoms, such as hexamethylene diisocyanate, dodecamethylene diisocyanate, and 2゜2.4-trimethylhexamethylene isocyanate; Diisocyanates and di(3-isocyanatepropyl) whose main chain is a group or a group derived from these
Examples include diisocyanates having an aliphatic hydrocarbon group to which an alkyl group is bonded via a divalent group or atom, such as ether.

These diisocyanates are not limited to one type, and two or more types can be used. When two or more types are used, a copolymer is obtained in which R in the general formula of the p P A is different. In the present invention, these copolymers can also be used.

The polyparabanic acid obtained as described above and used in the present invention usually has a degree of polymerization of 20 to 4000, and the intrinsic viscosity [TI] of polyparabanic acid with such a degree of polymerization is
30°C, 05% by weight dimethylformamide solution) is usually within the range of 0.1 to 3.0 dI2/g, but for the formation of the back coat layer, η is 02 to 1.5 d! /g, preferably 0.4 to 0.8 dff/g.

The polyparabanic acid in the present invention may have its terminal modified with a modifier. Examples of modifiers include carboxylic acid anhydrides, allyl group-containing compounds such as allyl alcohol, and allyl amine.

In the present invention, a reaction product of a silicone compound having a reactive group and an organic diisocyanate is blended with the polyparabanic acid.

Examples of the silicone compound having the reactive group used in the present invention include silicone compounds having an amino group, a carboxyl group, an oxy group, or a mercapto group in any of the side chains of the molecule terminal J.

Specific examples include the following.

(I) Structural formula of silicone oil having an amino group % Formula % n = 0 to 200 n: 1 to 200 (C) n = 1 to 200 Silicone oil having a carboxyl group Structural formula of silicone oil having an oxy group Structural formula +A) m: 1-10 n: 2-10 n=1-200 n: 1-200 fc) (4) Silicone oil having mercapto group Structural formula % Formula % As the organic diisocyanate used in the present invention, the above-mentioned PPA The general formula 0CN-R used in the production of
An organic diisocyanate represented by -NGO [R is the same as above] can be exemplified.

In the present invention, the reaction ratio [(b)/(a)] between the silicone compound (a) and the organic diisocyanate (b)
is the molar ratio of functional groups, and is suitably set to 0.4 to 1.

If the molar ratio is less than 0.04, unreacted silicone will be produced, and when a coating film is prepared from the resulting varnish, the silicone will float, making it difficult to use it as a back coat layer. On the other hand, when the molar ratio exceeds 1, the resulting varnish has a problem of increased viscosity and poor stability.

Further, the reaction conditions between the silicone compound and the organic diisocyanate vary depending on the type of the silicone compound and cannot be generally specified, but usually the reaction temperature is -10°C to +150°C and the reaction time is 0.5 to 5 hours. is within the range of

In the present invention, the blending ratio of the reaction product of (I) PPA, (I[) reactive silicone compound, and organic diisocyanate is 100 km to 100 km of the (I) site,
It is appropriate that (II) be 0.5 to 30 (weight ratio).

If the reaction product (II) is less than 0.05 with respect to PPA 100, improvement in slipperiness tends to be insufficient, while when it exceeds 30, heat resistance tends to be insufficient.

An organic solvent may be used to coat the base material to form a coating film. A varnish containing PPA and the above reaction product in an organic solvent. The concentration of the reaction product in the zunis is usually 1 to 15% by weight.

Examples of the organic solvent used in preparing the varnish include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide, γ-butyrolactone, cyclopentanone, and cyclohexanone. Two or more types of these may be used. Also,
In order to increase the drying rate of the varnish, a low boiling point solvent such as tetrahydrofuran (THF), methyl ethyl ketone (MEK), 1-toluene, ethyl acetate, dioxane, acetone, methyl cellosolve, ethyl cellosolve may be mixed with the above solvent. good.

When preparing the varnish, commonly used polyester, polyurethane, etc. may be added to the varnish, if necessary, in order to improve the adhesion to the base material.

Any method can be used to form a coating film on the back side of the base material, but there are two methods: coating the varnish on the base material, drying and heat-treating it, and casting the varnish on the base material and then drying it. , heat treatment, etc. are common methods. The drying may be carried out under heating, and the heat treatment is preferably carried out at a temperature of 50 to 150°C.

The thickness of the coating film is generally preferably 0.1 to 1100 LL.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Silicone oil having amine groups at both ends [Structural formula (I) (C) above, manufactured by Shin-Etsu Chemical Co., Ltd., trade name X-22-16
1A] was added to 100 g of DMF, and cooled (O
℃~5℃) A solution of 7.4 g of MDI dissolved in DMF was added. The reaction was carried out under cooling for 1 hour, and after cooling was discontinued, stirring was continued until the temperature returned to room temperature.

When the infrared absorption spectrum of the obtained reaction product solution was examined, no absorption spectrum due to isocyanate groups at 2270 cm-' was observed.

Next, PPA (hereinafter referred to as PPA-M) synthesized using MDI as an organic diisocyanate (r) inh = 0.4, measured at 30 °C in DMF)
A varnish was prepared by adding 1 g of the previously obtained reaction product i@ solution to a solution of 5 g dissolved in 95 g of DMF and stirring well.

This varnish was applied onto a 6 μm thick PET film as No. 3.
It was applied using a bar coater.

After drying in an oven at 120° C. for 15 minutes, the performance of the resulting coating film (slipness and heat resistance of the coating film) was examined.

The results are shown in Table 1.

Example 2 Silicone oil having oxy groups at both ends [Structural formula (3) (A), manufactured by Shin-Etsu Chemical Co., Ltd., trade name KF6002]
Add 50g to 100g of DMF and heat (I20
℃) A solution of 3.2 g of TODI was added to 30 g of DMF.

After reacting at 120° C. for 1.5 hours, heating was stopped, and stirring was continued until the reaction solution returned to room temperature.

When the infrared absorption spectrum of the obtained reaction product solution was examined, no absorption spectrum of incyanate groups was observed.

Next, 5 g of PPA-M (n inh =0.6) synthesized in the same manner as in Example 1 was added to 95 g of DMF.
A varnish was prepared by adding 1 g of the previously obtained reaction product solution to the solution dissolved in the solution and stirring well.

In the same manner as in Example 1, a varnish was applied onto a PET film, and the performance of the resulting coating film was examined.

The results are shown in Table 1.

Example 3 Silicone oil having meltcapto groups at both ends [Structural formula (4) (C) above, manufactured by Shin-Etsu Chemical Co., Ltd., product name X-22
150 g of -167B was added to 100 g of DMF, and a solution of 3.0 g of MDI dissolved in 30 g of DMF under heating (I00° C.) was added. After carrying out the reaction at 100°C for 15 hours,
Heating was stopped, and stirring was continued until the reaction solution returned to room temperature.

When the infrared absorption spectrum of the obtained reaction product solution was examined, no absorption spectrum of isocyanate groups was observed.Next, 5g of PPA-M used in Example 1 was dissolved in DMF9.
A varnish was prepared by adding 1 g of the previously obtained reaction product droplets to 5 g of the solution and stirring well.

Apply varnish on the PET film in the same manner as in Example 1,
The performance of the resulting coating film was investigated.

The results are shown in Table 1.

Comparative Example 1 5 g of PPA-M used in Example 1 was dissolved in 95 g of DMF to prepare a varnish.

Apply varnish on the PET film in the same manner as in Example 1,
The performance of the resulting coating film was investigated.

The results are shown in Table 1.

Comparative Example 2 5 g of the silicone oil used in Example 1 was added to 20 g of DMF, and 0.64 g of MDI was added, followed by thorough stirring at room temperature. DMF3 for 10 parts of the obtained reaction solution
A varnish was prepared by adding 0 parts.

Apply varnish on the PET film in the same manner as in Example 1,
The performance of the resulting coating film was investigated.

The results are shown in Table 1.

Table 1 According to the present invention, a back coat coating film with good heat resistance, good surface smoothness, small friction coefficient, and improved slip properties can be obtained, which is particularly required for thermal transfer ribbons. We were able to satisfy the following properties: good heat resistance, good lubricity, and resistance to adhesion to the thermal head.

11: PPA coating surfaces to ASTM D1894-6
Measured according to 3.

2): Observe whether fusion occurs or not by hot pressing at 250°C.

O: Not fused X: fused As is clear from Table 1, the coating films obtained in Examples 1 to 3 had good slipperiness and sufficient heat resistance, making them suitable as back coats for thermal transfer ribbons. It is clear that it is effective.

[Effect of the invention〕 Patent applicant: Tonen Petrochemical Co., Ltd. Nitto Chemical Industry Co., Ltd. Representative Patent Attorney Yoshihiro Sato

Claims (1)

[Claims] 1. A back coat coating film applied to the back side of a base material constituting a heat-sensitive recording material such as a thermal transfer ribbon, comprising (I) polyparabanic acid and (II) silicone having a reactive group. A heat-sensitive recording material backcoat film comprising a mixture of a compound and a reaction product of an organic diisocyanate. 2. Consisting of a base sheet, a heat-sensitive recording layer provided on the surface of the base sheet, and a back coat coating film provided on the back surface of the base sheet, the back coat coating film containing (I) polyparabanic acid, and ( II) A thermal transfer ribbon comprising a mixture of a reaction product of a silicone compound having a reactive group and an organic diisocyanate.